1. Technical Field
The present invention relates to an exterior environment recognition device for recognizing environment outside of a subject vehicle, and, more particularly, relates to an exterior environment recognition device for detecting dirt or fog adhered to optical components and the windshield and appropriately processing an image according to a detection result.
2. Related Art
There have been known exterior environment recognition devices such as one described in Japanese Unexamined Patent Application Publication (JP-A) No. 2010-224925. The exterior environment recognition device has an onboard camera mounted on a vehicle to capture an image of road environment in front of a subject vehicle, and detects light sources such as a traffic light and a brake lamp on the basis of color information and position information in the image.
When a light source is detected using color information in an image as described above, the following problem may occur: if strong environment light such as sunlight (image capturing against the sunlight) is emitted in the image-capturing direction while there is dirt or fog on a transparent body such as a windshield located in the image-capturing direction and an optical component such as a lens, then, the color component of the environment light is added to the entire captured image, and this causes the target object in the image to have a color different from the original color. As a result, the recognition accuracy of the light source using the color information is reduced, or it becomes impossible to recognize the light source.